Detecting unauthorized access to a wireless network

ABSTRACT

Systems and methods detect a potential hacking attack by monitoring the number and timing of DELBA (Delete Block Acknowledgement) action frames. When the number and timing of the DELBA action frames correspond to an unauthorized access pattern, an unauthorized access is detected. The potential unauthorized access may be detected by an access point (AP) or by the AP and a backend system. When a potential unauthorized access is detected, the AP may remain in silent mode for a longer period of time and limit access to the network to only trusted devices. In addition, an alarm or other notification of the potential unauthorized access may be provided to a user or other designated contact.

FIELD OF THE INVENTION

This application relates to network security and in particular to detecting a potential unauthorized access to a wireless network by monitoring DELBA action frames.

BACKGROUND

Wifi technology is commonly used to provide wireless broadband service in a home or other environment. Devices and systems, including entertainment systems, may communicate with a wireless Access Point (AP) to access a Wifi network. Network security is a concern for Wifi networks. In some systems, network security is provided by having the AP maintain a list of trusted devices and allowing only those trusted devices access to the network.

An unauthorized device that is attempting to access the network, i.e., a hacking device, may be able to obtain security keys, such as WEP/WPZ/WPS keys and access the network or conduct other network-based attacks on wireless or Ethernet-based networks. When a Wifi network is hacked, it may expose information from a network customer or network provider or it may allow the hacker to control other devices on the network.

SUMMARY

Aspects of the invention provide systems and methods for detecting a potential hacking attack by monitoring the number and timing of DELBA (Delete Block Acknowledgement) action frames. When the number and timing of the DELBA action frames correspond to an unauthorized access pattern, an unauthorized access is detected. An unauthorized access pattern may specify a threshold number of DELBA action frames within a predetermined time interval or a pattern of DELBA action frames. The factors used to detect a potential unauthorized access, such as the number of DELBA action frames and the time interval, may be adaptive and may be adjusted as needed.

When a potential unauthorized access is detected, the wireless access point (AP) enters defensive mode. While in defensive mode, the AP may remain in silent mode for a longer period of time than normal and limit access to the network to only trusted devices. In addition, an alarm or other notification of the potential unauthorized access may be provided to a user or other designated contact.

These illustrative aspects and features are mentioned not to limit or define the invention, but to provide examples to aid understanding of the inventive concepts disclosed in this application. Other aspects, advantages, and features of the present invention will become apparent after review of the entire application.

BRIEF DESCRIPTION OF THE DRAWINGS

The features, aspects, and advantages of the present disclosure are better understood when the following Detailed Description is read with reference to the accompanying drawings.

FIG. 1 is an block diagram illustrating exemplary operations of an AP and backend system when the AP is configured to detect a potential unauthorized access.

FIG. 2 is a block diagram illustrating exemplary operations of an AP and backend system when the backend system is configured to detect a potential unauthorized access.

FIG. 3 is a block diagram illustrating an exemplary operating environment for detection and notification of a potential unauthorized access.

DETAILED DESCRIPTION

A potential hacking attack may be identified by monitoring the number and timing of DELBA (Delete Block Acknowledgement) action frames to determine whether the DELBA action frames correspond to an unauthorized access pattern. An unauthorized access pattern may specify a threshold number of DELBA action frames within a predetermined time interval or a pattern of DELBA action frames. When the DELBA action frames match the unauthorized access pattern, a potential hacking attack is identified and a wireless access point (AP) enters a defensive mode. While in defensive mode, the AP may enter silent mode and optionally may limit access to the network to only trusted devices.

The AP may be configured to enter silent mode in response to detecting a DELBA event or a DELBA action frame when operating under normal conditions. When the AP enters silent mode under normal conditions, it may remain in silent mode for a default time period. In one example, the default time period is approximately 30 seconds to 1 minute. An AP may enter silent mode a few times a day under normal conditions. For example, heavy traffic conditions may cause the AP to enter silent mode.

When the DELBA action frames correspond to an unauthorized access pattern, then a potential hacking attack may be detected. The unauthorized access pattern may specify a threshold number of DELBA action frames detected within a time interval or another pattern that is indicative of a potential hacking attack. In one implementation, the AP or a wireless home router determines that conditions indicate a potential hacking attack. In another implementation, a wireless home cloud router or a backend system determines that conditions indicate a potential hacking attack.

FIG. 1 illustrates a configuration where a wireless home router determines whether conditions indicate a potential hacking attack and if so, enters a defensive mode. In this example, the router is an AP. The AP 102 may be located in a home or other customer location and may be capable of communicating with devices 130, 140 and with backend system 150. In the example illustrated by FIG. 1, device 140 is a trusted Wifi client device and device 130 is a hacking device.

The blocks 110-120 within the AP 102 illustrate operations performed by the AP. Each block may correspond to one or more components in the AP and may be implemented in firmware, hardware, software, or any combination thereof. The AP may include a Wifi interface or RF front end 110 for wirelessly communicating with devices, such as devices 130, 140, and providing the devices with access to the network. The AP monitors communications received from the devices. When the AP detects a DELBA action frame in block 112, it sets a DELBA flag in block 114. It may also allocate memory for the DELBA flag in block 114, if needed. The AP may maintain a counter of DELBA action frames or flags that is adjusted each time a DELBA action frame is detected. In block 116, the AP determines whether the number or pattern of DELBA action frames indicates a potential unauthorized access.

In one example, the AP may use a threshold of 3 DELBA action frames within a 15 minute time interval to identify a potential unauthorized access. If 3 or more DELBA action frame flags occur within 15 minutes, i.e., the AP enters silent mode at least 3 times in 15 minutes, then a potential hacking attack is detected. A hack flag is set in block 116 and the AP enters defensive mode. The number of DELBA action frames and/or the length of the time interval may be adjusted as additional data about the operation of the AP or hacking behaviors are obtained.

In another example, a potential hacking attack may be detected when the AP cycles between normal mode and silent mode according to a predetermined pattern, such as alternating between silent mode for 1 minute and then normal mode for 1 minute for a certain number of minutes or a certain number of times. The pattern may be selected so that it corresponds to the known or expected behavior of an AP during a potential hacking attack. When the pattern is detected, the hack flag is set in block 116 and the AP enters defensive mode. The pattern may be adjusted as additional data about the operation of the AP or hacking behaviors are obtained.

While in defensive mode, the AP enters silent mode in block 118 and remains in silent mode for a defensive time period. The AP may remain in silent mode for a longer period of time while in defensive mode than when it is enters silent mode under normal conditions. In one exemplary implementation, the AP remains in silent mode for 30 seconds when it enters silent mode under normal conditions and remains in silent mode for 1 minute when it enters silent mode while in defensive mode. Alternatively, the AP may remain in silent mode for a period of time that is the same as or similar to the default time period. In another exemplary implementation, the AP remains in silent mode for 1 minute when it enters silent mode under normal conditions and remains in silent mode for 1 minute when it enters silent mode while in in defensive mode.

In addition to entering silent mode, the AP may also notify the backend system of the potential unauthorized access. In one example, the AP sends a TR69 message to the backend system to notify the backend system of the potential unauthorized access. TR69 is an application layer protocol for remote management of customer-premises equipment (CPE), such as a router. Other protocols for communication between a remote device and a backend system may also be used. The backend system may communicate information about the potential unauthorized access to a monitoring center, may generate an alarm or other notification, may notify a customer or other contact associated with the AP, or take any other suitable action.

While the AP is in defensive mode, it may not allow devices, such as devices 130, 140 access to the network. Alternatively, while the AP is in defensive mode, it may allow only trusted devices access to the network. A trusted devices may be recognized by the AP by its MAC address. In one implementation, the AP maintains a list of trusted MAC addresses. While the AP is in defensive mode, the AP may allow device 140 access to the network when the MAC address for device 140 is included on the list of trusted MAC addresses in block 120. If trusted devices are permitted to access the network during silent mode, the AP continues to monitor DELBA action frames in block 112. The AP may prevent device 130 from accessing the network when the MAC address for the device is not included on the list of trusted MAC addresses. In some implementations, if a device with an untrusted MAC addresses tries to communicate with the AP while the AP is in defensive mode, the AP may take additional action including, but not limited to, extending the defensive time period or sending a further message to the backend system. Once the AP exists defensive mode, it exists silent mode and may communicate with devices regardless of whether they are recognized as trusted devices.

If the AP does not detect a potential hacking attack in block 116, it enters silent mode in block 118, but does not enter defensive mode. It remains in silent mode for a default time period and then exists silent mode. After it exists silent mode, it may communicate with devices 130, 140.

FIG. 2 illustrates an implementation where a cloud router determines whether conditions indicate a potential unauthorized access. The AP 202 may communicate with devices 230, 240. In the example illustrated by FIG. 2, device 240 is a trusted Wifi client device and device 230 is a hacking device. The AP 202 also communications with a backend system 250.

The blocks 210-216 within the AP 102 illustrate operations performed by the AP. Each block may correspond to one or more components in the AP and may be implemented in firmware, hardware, software, or any combination thereof. The blocks 218-224 within the backend system illustrate operations performed by the backend system. Each block may correspond to one or more components in the backend system and may be implemented in firmware, hardware, software, or any combination thereof.

The AP may include a Wifi interface or RF front end 210 for wirelessly communicating with devices 230, 240, and providing the devices with access to the network. The AP monitors communications received via block 210. When the AP detects a DELBA action frame in block 212, it sends a communication to the backend system in block 214 that indicates a DELBA action frame has been detected. In one implementation, the communication is a TR69 compliant message. The AP also enters silent mode when it detects a DELBA action frame.

The backend system receives the communication from the AP at block 218 via an AP interface and sets a DELBA flag in block 219. If necessary, the backend system may allocate memory for the DELBA flag. The backend system may also maintain a counter of DELBA action frames or flags that is adjusted each time it receives a communication from the AP indicating that a DELBA action frame has been detected. In block 220, the backend system determines whether the number or pattern of DELBA action frames indicates a potential unauthorized access. The backend system may use a threshold of DELBA action frames within a time interval or a pattern of DELBA action frames to detect a potential hacking attack, similar to those discussed above in connection with FIG. 1.

If the backend system detects a potential unauthorized access, then it sets a hack flag in block 220. It also determines that the AP should enter defensive mode in block 222. It sends a message to the AP in block 218 with a flag or other indicator to inform the AP that a potential hacking attack has been detected and/or a command instructing the AP to enter defensive mode. In one example, the message may be a TR69 compliant message.

Upon receiving the message the AP enters defensive mode. In one example, the AP enters silent mode when it detected the DELBA action frame and is still in silent mode when it receives the message from the backend system. In this example, the AP remains in silent mode for the defensive time period. In another example, the AP is not in silent mode when it receives the message from the backend system. In this example, the AP enters defensive mode and enters silent mode in response to receiving the message from the backend system. It remains in silent mode for the defensive time period.

In either example, while in defensive mode the AP may prevent devices from accessing the network or may only allow trusted devices to access the network. The AP may use the MAC address of a device to determine whether the device is a trusted device, as discussed above in connection with FIG. 1.

If the backend system detects a potential unauthorized access, then it may communicate information about the potential unauthorized access to a monitoring center, may generate an alarm or other notification, may notify a customer or other contact associated with the AP, or take any other suitable action.

FIG. 3 illustrates how notice of the potential unauthorized access may be provided. Once the home or cloud router 302 detects a potential unauthorized access, the router may send a message to a server 350. The server may include or further communicate with a messaging system 352. The messaging system may store information about the router, including a customer profile that specifies how to communicate information about a potential unauthorized access. For example, the customer profile may specify that a message or alert should be sent to the customer and/or another listed contact when a potential unauthorized access is detected. The messaging center may send the message or alert in real-time to one or more wireless devices 354. The message may include information about the potential unauthorized access including, but not limited to, the MAC address of the device identified as the potential hacking device.

The server may also include or be connected to a monitoring system. The monitoring system may monitor information about potential unauthorized accesses and may analyze the data to determine whether to adjust any of the factors used to detect a potential unauthorized access. The factors for determining a potential unauthorized access may be adaptive and may use maximum likelihood criteria that depends on the environment, the RF link, patterns and behaviors associated with confirmed hacking attacks, etc. Factors, such as the number of DELBA action frames, the duration of the time interval, the pattern of DELBA action frames, and the defensive time period may be updated based on the information collected by the monitoring system. The monitoring system may send the updated values to the AP or to the server depending upon where the determination of a potential unauthorized access is made. The monitoring system may also modify the actions taken by the AP while in defensive mode by sending a message to the AP. For example, the value for the defensive time period or the list of trusted MAC addresses may be updated.

The operations described above may be performed by firmware, hardware, and/or software. In some implementations, the operations are performed by one or more processing devices in the AP or the backend system executing computer readable instructions stored on computer readable media.

The foregoing description of the examples, including illustrated examples, of the invention has been presented only for the purpose of illustration and description and is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Numerous modifications, adaptations, and uses thereof will be apparent to those skilled in the art without departing from the scope of this invention. For example, the messages sent between the AP and the backend system, are not limited to TR69 compliant messages and may use a different protocol. The illustrative examples described above are given to introduce the reader to the general subject matter discussed here and are not intended to limit the scope of the disclosed concepts. 

What is claimed is:
 1. A method for managing access to a wireless network, comprising: receiving a communication from a wireless device, at a wireless access point; processing the communication to determine whether the communication corresponds to a DELBA action frame; when the communication corresponds to a DELBA action frame, then determining whether the DELBA action frame and at least one preceding DELBA action frame correspond to a predetermined unauthorized access pattern; and when the DELBA action frame and the at least one preceding DELBA action frame correspond to the predetermined unauthorized access pattern, then detecting a potential unauthorized access and configuring the wireless access point to enter a defensive mode, wherein while in defensive mode the wireless access point enters silent mode and remains in silent mode until a defensive time period expires.
 2. The method of claim 1, further comprising: while in defensive mode, the wireless access point receives a second communication; the wireless access point compares a MAC address associated with the second communication to a list of trusted MAC addresses; and when the MAC address associated with the second communication corresponds to a MAC address on the list of trusted MAC addresses, then the wireless access point allows access to the wireless network.
 3. The method of claim 2, further comprising: when the MAC address associated with the second communication does not corresponds to a MAC address on the list of trusted MAC addresses, then the wireless access point denies access to the wireless network.
 4. The method of claim 1, further comprising: when the DELBA action frame and the at least one preceding DELBA action frame do not correspond to the predetermined unauthorized access pattern, then configuring the wireless access point to enter silent mode and remain in silent mode until a default time period expires, wherein the default time period is shorter than the defensive time period.
 5. The method of claim 1, wherein the predetermined unauthorized access pattern specifies a number of DELBA action frames received within a time interval.
 6. The method of claim 1, wherein the predetermined unauthorized access pattern specifies an alternating sequence of a silent mode period and a non-silent mode period that repeats a predetermined number of times.
 7. The method of claim 1, further comprising: in response to detecting a potential unauthorized access, sending a message to a user alerting the user to the potential unauthorized access.
 8. A wireless access point, comprising: a wireless interface for communicating with a plurality of wireless devices; a memory for storing computer-readable instructions; and a processing device for executing the computer-readable instructions to configure the wireless access point for: receiving a communication from a wireless device via the wireless interface; processing the communication to determine whether the communication corresponds to a DELBA action frame; when the communication corresponds to a DELBA action frame, then determining whether the DELBA action frame and at least one preceding DELBA action frame correspond to a predetermined unauthorized access pattern; and when the DELBA action frame and the at least one preceding DELBA action frame correspond to the predetermined unauthorized access pattern, then detecting a potential unauthorized access and configuring the wireless access point to enter a defensive mode; while in the defensive mode the wireless access point enters silent mode and remains in silent mode until a defensive time period expires; and sending a message to a backend system that indicates that the wireless access point detected a potential unauthorized access.
 9. The wireless access point of claim 8, wherein the processing device further configures the wireless access point for: while in the defensive mode, receiving a second communication via the wireless interface; comparing a MAC address associated with the second communication to a list of trusted MAC addresses; and when the MAC address associated with the second communication corresponds to a MAC address on the list of trusted MAC addresses, then allowing access to a wireless network.
 10. The wireless access point of claim 9, wherein the processing device further configures the wireless access point for: when the MAC address associated with the second communication does not corresponds to a MAC address on the list of trusted MAC addresses, then preventing access to the wireless network.
 11. The wireless access point of claim 9, wherein the processing device further configures the wireless access point for: when the DELBA action frame and the at least one preceding DELBA action frame do not correspond to the predetermined unauthorized access pattern, then configuring the wireless access point to enter silent mode and remain in silent mode until a default time period expires, wherein the default time period is shorter than the defensive time period.
 12. The wireless access point of claim 9, wherein the predetermined unauthorized access pattern specifies a number of DELBA action frames received within a time interval.
 13. The wireless access point of claim 12, wherein the processing device further configures the wireless access point for: receiving an update communication from a server with an updated value for the number of DELBA action frames or an updated duration of the time interval; and adjusting the predetermined unauthorized access pattern with the updated value for the number of DELBA action frames or the updated duration of the time interval.
 14. The wireless access point of claim 9, wherein the predetermined unauthorized access pattern specifies an alternating sequence of a silent mode period and a non-silent mode period that repeats a predetermined number of times.
 15. A server in communication with a wireless access point, comprising: an access point (AP) interface for communicating with the wireless access point; a memory for storing computer-readable instructions; and a processing device for executing the computer-readable instructions to configure the server for: receiving a communication from the wireless access point via the AP interface, wherein the communication indicates the wireless access point has detected a DELBA action frame; determining whether the DELBA action frame and at least one preceding DELBA action frame correspond to a predetermined unauthorized access pattern; and when the DELBA action frame and the at least one preceding DELBA action frame correspond to the predetermined unauthorized access pattern, then detecting a potential unauthorized access; sending a communication to the wireless access point to enter a defensive mode; and initiating a message to a user system providing notice of the potential unauthorized access.
 16. The server of claim 15, wherein sending a communication to the wireless access point to enter a defensive mode includes sending a value for a defensive time period.
 17. The server of claim 15, wherein the predetermined unauthorized access pattern specifies a number of DELBA action frames received within a time interval.
 18. The server of claim 17, wherein the processing device further configures the server for: adjusting a value for the number of DELBA action frames or a duration of the time interval; and updating the predetermined unauthorized access pattern with the adjusted value for the number of DELBA action frames or the adjusted duration of the time interval.
 19. The server of claim 15, wherein the predetermined unauthorized access pattern specifies an alternating sequence of the wireless access point entering a silent mode period triggered by a detected DELBA action frame and the wireless access point entering a non-silent mode period that repeats a predetermined number of times. 